Image reconstruction is a related art technique that encompasses the entire image formation process and provides a foundation for the subsequent steps of image processing. The goal is to retrieve image information that has been lost in the process of image formation. In optical interference imaging techniques, interferograms of an object are generally converted into a wrapped phase map containing phase values in the range 0˜2π using a phase-shift algorithm. Three types of noise (residual noise, speckle noise, and noise at the lateral surface of height discontinuities) influence image reconstruction. Speckle noise is usually generated due to the laser source. Residual noise is the noise induced by environmental effects or contamination of the optical system. The depth of field limit and the diffraction limit influence the optical measurement range, especially for microscope interferometers. For the object containing height discontinuities, the interferograms of the object will blur when the height of the object is out of the depth of field. Therefore, the blur of the interferograms at the height discontinuities will be converted into noise in the wrapped phase map.
The wrapped phase maps are unwrapped by phase unwrapping algorithms. The phase unwrapping algorithms are classified as temporal, spatial and period-coding. Furthermore, the spatial phase unwrapping algorithms are classified as path-dependent algorithms (for example, MACY algorithm) and path-independent algorithms (for example, CA (cellular automata) algorithm). In these phase unwrapping algorithms, the noise problems in the process of image reconstruction generate error, known as the noise error. Various filtering algorithms are used to remove the noise error. The 2π phase jumps are smeared by filtering algorithms and produce an error known as the shifting error. The shape of holes present in objects also influences the image reconstruction and produce an error known as the hole error.
Most of the phase unwrapping algorithms are based on the shifting 2π method and are designed complexly in order to be efficient only for the phase values and therefore, the noise error, the shifting error and the hole error still exist.
Thus, there is an unmet need for generating a successful image reconstruction free from the noise error, the shifting error and the hole error.